781.

ON THE REMEDY FOR EARTHQUAKES.

The arch which throws its pressure perpendicularly on the abutments
will fulfil its function whatever be its direction, upside down,
sideways or upright.

The arch will not break if the chord of the outer arch does not
touch the inner arch. This is manifest by experience, because
whenever the chord a o n of the outer arch n r a approaches the
inner arch x b y the arch will be weak, and it will be weaker in
proportion as the inner arch passes beyond that chord. When an arch
is loaded only on one side the thrust will press on the top of the
other side and be transmitted